Phragmite des joncs

Identification

This is a medium-sized warbler, 11.5–13 cm (4.5–5.1 in) long and weighing around 12 g (0.42 oz). It has a streaked brown back and wings, and pale underparts. The rump is warm brown and unstreaked, contrasting with the duller wings. The forehead is flattened, the crown is streaked with black, and the bill is strong and pointed. There is a prominent whitish supercilium. The legs are greyish.<p>The plumage of the sexes is identical, although they can be told apart when caught for ringing by the presence of a brood patch or cloacal protuberance. Juvenile birds have dark spots on the breast. They can be easier to confuse with aquatic warblers due to an apparent pale central crown stripe contrasting with the darker edges. Other similar species include moustached warblers and Pallas's grasshopper warblers. The oldest recorded sedge warbler was a bird ringed in Finland which reached the age of 10 years, 1 month. The typical lifespan is 2 years.<p>The song is varied, rushed and chattering, with sweeter phrases and some mimicry, typical of the Acrocephalus warblers. It is composed of phrases in random order, so that it is never the same. Male sedge warblers which have the widest repertoire mate with the largest number of females.

Taxonomie

The sedge warbler was formally described by the Swedish naturalist Carl Linnaeus in 1758 in the tenth edition of his Systema Naturae under the binomial name Motacilla schoenobaenus. The species is now placed in the genus Acrocephalus that was introduced in 1811 by Johann Andreas Naumann and his son Johann Friedrich Naumann. British ornithologists did not distinguish the species from the Eurasian reed warbler until the 18th century. The genus name Acrocephalus is from Ancient Greek akros, "highest", and kephale, "head". It is possible that the Naumanns thought akros meant "sharp-pointed". The specific schoenobaenus is from Ancient Greek skhoinos, "reed", and baino, "to tread". It is a translation of the old Swedish name for the bird, Sävstigare. The species is considered to be monotypic: no subspecies are recognised.

Nom scientifique

Acrocephalus schoenobaenus

Autorité

(Linnaeus, 1758)

Ordre

Passériformes

Famille

Acrocephalidae

Genre

Acrocephalus

Répartition et habitat

The sedge warbler has a large range and an estimated Global Extent of Occurrence of 10 million square kilometres, with a large global population including between 8.8 million and 15 million birds in Europe. Data analysis by the British Trust for Ornithology has shown that fluctuations in the sedge warbler population stem from the adult survival rate, due to changes in rainfall on the birds' wintering grounds. Global changes in population have not been measured, but the sedge warbler's status is designated 'of least concern' by BirdLife International.<p>It breeds across Europe and western and central Asia and is migratory. After feeding up post-breeding, they migrate quickly across southern Europe and the Sahara from August to September. Studies in Nigeria and Uganda suggest that sedge warblers return to spend winter at the same sites, year after year.<p>All sedge warblers spend winter in sub-Saharan Africa, from Senegal in the west to Ethiopia in the east, and as far south as the eastern Cape Province of South Africa and northern Namibia. The routes taken on the southward migration, and their eventual wintering grounds, correspond to the birds' breeding grounds. Birds ringed in the United Kingdom and Netherlands are later found from south-west Iberia to Italy; birds from Sweden are recovered in central Europe and Italy; while Finnish birds are found in north-east Italy and Malta east to the Aegean region. Sedge warblers from the former Soviet Union take routes via the eastern Mediterranean Sea and Middle East.<p>Loss of wetland areas for feeding on migration, and the expansion of the Sahara desert, pose threats to the sedge warbler's breeding population. Birds begin leaving Africa in late February, fatten up at wetlands before and probably after crossing the Sahara, and arrive in Europe from March onwards.<p>Unlike other members of the Acrocephalus genus, the sedge warbler's range stretches from the Arctic to mid-latitudes. It is adapted to cool, cloudy and moist conditions. Though it is often found in wetlands, it can breed 500 metres or more away from water. During the breeding season, this is a species found in reedbeds, often with scrub, ditches and habitats away from water including hedgerows, patches of stinging nettles, and arable crops. On the African wintering grounds, habitats such as reeds at wetlands, papyrus, grass, sedge and reedmace and tall elephant grass are used. It can be found at altitudes of 1,800–2,400 metres above sea level in Ethiopia.

Aire de reproduction

PAL : w, n, c Europe to c Russia

Aire hors reproduction

Sub-Saharan Africa

Migration

Migrateurs complets

Comportement

Mode de migration: Migrateurs complets.

Conservation

Tendance de la population: stable.

Tendance de la population

stable